Fluid driven drills such as by either air or water are known in the art. A preferred application for such types of drills is in dental work since there is no electricity involved at the portion of the instrument placed in a person's mouth. Moreover, very high speeds can be obtained utilizing air or water turbines to drive the drill.
Other applications for high speed drills is in the drilling of printed circuit boards. Thus rather than a hand held drill motor, these applications would normally involve a permanently mounted motor in a circuit drilling machine mechanism.
While the foregoing described motors have been satisfactory, their life is severely limited by the life of bearings utilized in rotatably mounting the rotor shaft carrying the drill or grinding tool or other instrument to be rotated. The enormously high speeds attainable by these drills simply cannot be handled by presently available mechanical type bearings. The only solution, accordingly, is to operate such drills at lower speeds or to redesign the bearings with expensive components far out of proportion of the overall cost of the tool and its particular job. Neither solution is really satisfactory.